1. Field of the Invention
The present invention relates to thin film sliders for use with magnetic data storage media such as disk and tape media. More particularly, the invention concerns a composite thin film slider with a protruding read/write ("R/W") device formed by chemical-mechanical polishing to protrude above its substrate and thereby reduce the magnetic spacing between the R/W device and the recording media.
2. Description of the Related Art
One of the most important parts of a tape or disk drive is its recording head, also called a "slider." The slider is one factor in determining the efficiency, density, speed, and accuracy with which data can be read from and written to magnetic recording media. As engineers are increasing the performance requirements of their recording systems, they are concurrently researching improved designs for sliders. One of the chief goals in designing a slider is minimizing the distance between the recording medium and the region of the slider that actually performs read and write operations, i.e. the R/W "device." This distance may be referred to as the "magnetic spacing." With a smaller magnetic spacing, the R/W device can store data more compactly on the recording medium, thereby increasing the recording medium's storage capacity.
One of the chief obstacles to reducing magnetic spacing is the difference in elevation between the slider's substrate and its R/W device. As discussed below, known techniques for lapping and polishing typically produce sliders with R/W devices that are eroded below the level of the adjacent substrate. This increases the magnetic spacing.
Sliders are typically derived from a wafer 100 (FIG. 1) composed of a substrate of "N58" (a titanium carbide (TiC) and aluminum oxide (Al.sub.2 O.sub.3) mix) and an overcoat comprising read/write device metallurgy and an insulator such as Al.sub.2 O.sub.3. Depending upon the size of the wafer 100 and the sliders to be cut, the wafer 100 may produce from 500 to 10,000 individual sliders. The components of each slider's R/W device are deposited onto a surface 102 of the wafer's substrate. These components include, for example, pole tips, magnetoresistive ("MR") elements, shields, and the like. These components are usually made from aluminum oxide, metals, or another material different than the substrate.
The next step in preparing an individual slider is to cut the wafer 100 into rows, such as the row 200 (FIG. 2). The row 200 has a "deposit end" 102 (corresponding to the surface 102 of FIG. 1 ) and a bearing surface 202. The row 200 may have dimensions of about 47 mm.times.2 mm.times.0.5 mm, for example. Next, the bearing surface 202 is smoothed by conventional lapping and polishing techniques to provide sliders with precise dimensions. After air bearing fabrication, the row 200 is then cut into individual sliders, such as the slider 300 (FIG. 3). The slider 300 includes a substrate 302 and a comparatively small R/W device, which is not shown but occupies an area 304 of the deposit end 102. The R/W device 304 is deposited along the deposit end 102 of the substrate 302. Prior to cutting the row 200 into individual sliders, the deposit end 102 of the individual slider 300 (FIG. 3) constituted part of the surface 102 of the row 200 (FIG. 2).
FIG. 4 illustrates the substrate 302 and the R/W device 304 in greater detail. The R/W device 304 includes an insulator 408, multiple shields 400-401, an MR stripe 402, and a pole tip 404. The slider 300 may also include a nearly uniform carbon overlayer 406 covering the substrate 302 and R/W device 304, to protect the slider 300 from wear, contamination, or damage.
For many applications, the slider 300 of FIGS. 3-4 satisfies its users' expectations. However, for applications requiring a higher recording density, known sliders may not be completely adequate. As shown in FIG. 4, known slider manufacturing processes yield a R/W device 304 that is recessed in elevation with respect to the bearing surface 202 of the substrate 302, usually by about 15-20 nm. Additionally, the shields 400-401, MR stripe 402, and pole tip 404 are recessed with respect to the insulator 408. Accordingly, when the slider 300 is implemented in a magnetic recording device, the critical components of the R/W device 304 may be excessively distanced from the recording medium (not shown), thereby reducing the slider's recording density.